(a) Field
The subject matter of this disclosure relates generally to a control method using a continuous variable valve duration apparatus, and more particularly to a control method using a continuous variable valve duration apparatus which can change opening duration of a valve using a simple configuration in accordance with operational states of an engine.
(b) Description of the Related Art
Generally, internal combustion engines generate power by receiving and burning air and fuel in a combustion chamber. An intake valve is operated by a camshaft, and air is charged into the combustion chamber while the intake valve is open. An exhaust valve is also operated by the camshaft, and air is discharged from the combustion chamber while the exhaust valve is open.
Optimal operation of the intake valve/exhaust valve, however, depends on the RPM of the engine. That is, an appropriate time for lifting or opening/closing the valves depends on the RPM of the engine. In order to implement an appropriate valve operation in accordance with the RPM of the engine, as described above, a CVVL (Continuously Variable Valve Lift) apparatus that has a plurality of different shapes of cams operating valves or that operates valves at different lifts in accordance with the RPM of an engine has been studied.
A CVVT (Continuous Variable Valve Timing) technique has been developed to adjust the opening duration of a valve, in which the timings of opening/closing a valve are simultaneously changed, with the valve duration being fixed.
However, the CVVL or the CVVT has a problem in that the configuration is complicated and the manufacturing cost high.
Originally, idle RPM of an engine is controlled by varying amount of air depending on operation of a throttle valve or changing ignition timing.
However, fuel consumption may deteriorate by inefficient driving of an engine while controlling idle RPM of an engine depending on ignition timing. In addition, there may be a limitation of vehicle speed while controlling idle RPM of an engine depending on the amount of air passing through a throttle valve.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.